Pneumatically-operated emergency isolation valve switchover kit

ABSTRACT

An emergency shutdown (ESD) system for a process control system includes an air supply coupled to a solenoid valve used to control a pneumatically-operated emergency isolation valve (ZV) via a switchover kit, a smart valve positioner coupled to the solenoid valve via the switchover kit, and an ESD controller. The ESD controller is configured to: control the supply of air from the air supply by the solenoid valve to open and close the ZV, and control the smart valve positioner so as to perform a partial stroke test on the ZV. The switchover kit includes a manifold having a plurality of valves coupling the air supply, the solenoid valve, and the smart valve positioner such that: based on a first setting of the plurality of valves, a first air flow path through the manifold connects the air supply directly to the solenoid valve, and based on a second setting of the plurality of valves, a second air flow path through the manifold connects the air supply to the solenoid valve through the smart valve positioner.

BACKGROUND

Pneumatically-operated emergency isolation valves (ZVs) are commonlyinstalled in hydrocarbon processing facilities to provide safe isolationof flammable or potentially toxic material in the event of a fire oraccidental release of fluids. The ZVs are operated locally though alocal control panel or automatically operated through an emergencyshutdown (ESD) system. The ZVs are normally in a fully opened or fullyclosed state. However, in order to assure that such ZVs can properlyfunction, the ZVs are periodically tested by partially opening orclosing the ZVs (i.e., using a partial stroke test). Because such testsare typically performed while the system is online and the process isrunning through the pipeline, it is important to perform any testquickly before returning the ZV to a normal operational state.

In conventional-type ESD systems, initially, only full stroke testingwas able to be performed. Over time, in order to perform a partialstroke test in conventional-type ESD systems, a complex panel ofpneumatic valves and switches were developed that needed to be manuallyused by an operator to partially open or close the ZV under test. Thiscomplicated action required an operator to fully understand andcarefully operate all of the pneumatic valves and switches associatedwith the ZV in order to partially open or close the ZV being tested.Also, it is critical that any ESD system be capable of quickly switchinginto a safe condition when so commanded because it is possible that afailure event could occur during a ZV partial stroke test and the ZVunder test would be required to quickly perform its safety function.

Accordingly, smart-type ZV systems have been developed in which anemergency shutdown (ESD) controller, using a smart valve positioner,automatically operates the pneumatic valves and switches associated withthe ZVs in order to perform partial stroke test on particular ZVs.Further, the ESD controller also monitors the process control system andautomatically switches the ZVs into a safe state in the event of afailure in the process control system. Even when not performing apartial stroke test, any of a number of failures in a smart valvepositioner can errantly cause drive the ZVs into a safe state.

SUMMARY

This summary is provided to introduce a selection of concepts that arefurther described below in the detailed description. This summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofthe claimed subject matter.

In one aspect, embodiments disclosed herein relate to an emergencyshutdown (ESD) system for a process control system comprising: an airsupply coupled to a solenoid valve used to control apneumatically-operated emergency isolation valve (ZV) via a switchoverkit, a smart valve positioner coupled to the solenoid valve via theswitchover kit, an ESD controller configured to: control the supply ofair from the air supply by the solenoid valve to open and close the ZV,and control the smart valve positioner so as to perform a partial stroketest on the ZV; wherein the switchover kit comprises: a manifold havinga plurality of valves coupling the air supply, the solenoid valve, andthe smart valve positioner such that: based on a first setting of theplurality of valves, a first air flow path through the manifold connectsthe air supply directly to the solenoid valve, and based on a secondsetting of the plurality of valves, a second air flow path through themanifold connects the air supply to the solenoid valve through the smartvalve positioner.

In one aspect, embodiments disclosed herein relate to a method foroperating and testing an emergency shutdown (ESD) system for a processcontrol system comprising: an air supply coupled to, via a switchoverkit, a solenoid valve used to control a pneumatically-operated emergencyisolation valve (ZV), a smart valve positioner coupled to the solenoidvalve via the switchover kit, an ESD controller configured to: controlthe supply of air from the air supply by the solenoid valve to open andclose the ZV, and control the smart valve positioner so as to perform apartial stroke test on the ZV; wherein the switchover kit comprises: amanifold having a plurality of valves coupling the air supply, thesolenoid valve, and the smart valve positioner, the method comprising:setting the plurality of valves in a first setting such that a first airflow path through the manifold connects the air supply directly to thesolenoid valve, setting of the plurality of valves in a second settingsuch that a second air flow path through the manifold connects the airsupply to the solenoid valve through the smart valve positioner,performing partial stroke tests on the ZV using the smart valvepositioner only when the valves of the manifold are set in the secondsetting, and operating the emergency shutdown system with the valves ofthe manifold set in the first setting at times when partial stroke testsare not being performed.

Other aspects and advantages of the claimed subject matter will beapparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of an emergency isolation valve system in ahybrid-type setup.

FIG. 2 is a diagram showing a switch from conventional-type tosmart-type operations in an emergency isolation valve system in ahybrid-type setup.

FIG. 3 is an embodiment of a switchover kit.

FIG. 4 is a flowchart showing operations of hybrid-type emergencyisolation valve system.

DETAILED DESCRIPTION

In one aspect, embodiments disclosed herein relate toinstrumentation/emergency shut-down valve control methods andapparatuses.

One or more embodiments relate to a pneumatically-operated emergencyisolation valve (ZV) switchover kit. The use of such a switchover kitmaintains the safety function of the ZV while preventing unintended ZVclosure caused by smart valve positioner failure, which can lead toprocess upsets and unnecessary flaring. Also, the use of such aswitchover kit provides a transfer mechanism to transfer a ZV fromconventional-type to smart-type and vice versa. The switchover kitmerges the advantages of conventional-type operations during normaloperations with the advantages of smart-type operations during timeswhen partial stroking is required. The transfer betweenconventional-type and smart-type operations can occur while the systemis online and running. Thus, the transfer does not impact safety orcause any process interruption.

As those skilled in the art will appreciate, ZVs are required to betested periodically to identify any potential failure(s) that couldprevent them from performing their intended function during an emergencyor process upset. Normally, ZV is fully stroked during plant shutdown.This shutdown requirement is not feasible at all times due to operationlimitations. Therefore, one option is to perform partial stroke testing(e.g., stroke only 10% valve opening) to extend the full stroke testrequirements up to nearest shutdown window. ZV partial stroke testing isa practice to ensure the functionality and reliability of the emergencyisolation valves (ZV's). However, partial stroke testing can only bedone by smart-type ZV setups.

Accordingly, there are generally two types of ZV setups available: aconventional-type ZV setup that merely controls opening/closing of theZV with an emergency shutdown (ESD) controller (without a smart valvepositioner) or a smart-type ZV setup that has an ESD controller foropening/closing the ZV and, additionally, is equipped with smart valvepositioner to improve the valve testing capabilities by providingpartial stroke testing capability. Conventional-type ZV setups require afull shutdown of operations in order to perform ZV testing. Smart-typeZV setups equipped with smart valve positioners allow automated, partialstroke testing of the ZVs so that operability can be tested whileoperations are still occurring.

There are typically massive numbers of both conventional-type andsmart-type ZV setups installed through the process control system, e.g.,at gas processing facilities. However, it is typical that most, if notall, critical paths within the process control system are installed withsmart-type ZV setups equipped with smart valve positioners that, whennecessary, are able to perform partial stroke tests without interruptingoperations. However, while such an arrangement is generally desirable,smart valve positioners are prone to failure and, as the number ofsmart-type ZV setups are installed increases, the number of failureoccurring in the smart valve positioners also increases. Failure of asmart valve positioner may result in the unintended closure of the ZVand can lead to process upsets and unnecessary flaring. Thus, it is inthe interest of maintaining continuous, safe, and stable operations tominimize such unintended ZV closures.

Referring to FIG. 1 , in accordance with one or more embodiments, a ZVsystem (100) is provided in a hybrid-type setup that includes aswitchover kit (102), i.e., a mechanism to change from aconventional-type ZV setup to a smart-type ZV setup. In the hybrid-typesetup of the ZV system (100), an air supply (104) is coupled to apneumatically-operated emergency isolation valve (ZV) (106) via theswitchover kit (102) and a solenoid valve (105). Further, a smart valvepositioner (108) is coupled to the air supply (104) via the switchoverkit (102), as well as coupled to the ZV (106) via a solenoid valve(105). When activated via the solenoid valve (105), the ZV (106) can beused to isolate process control equipment (112A) from process controlequipment (112B) in the event of an emergency.

Also, an emergency shutdown (ESD) controller (110) is connected to theZV system (100) and is configured to control the supply of air from theair supply (104) by the solenoid valve (105) to open and close the ZV(106). Further, the ESD controller is connected to the smart valvepositioner (108), which can be used to control the supply of air fromthe air supply (104) to the solenoid valve (105) so as to perform apartial stroke test on the ZV (106). The ESD controller may also beconfigured to control the switchover kit (102) to switch from a firstair flow path that connects the air supply (104) directly to thesolenoid valve (105) and a second air flow path that connects the airsupply (104) to the solenoid valve (105) through the smart valvepositioner (108). Alternatively, in one or more embodiments, theswitchover kit (102) may be manually controllable, or controlled by aseparate switchover kit controller, so that the switchover kit (102) canbe used to convert an existing smart-type ZV setup into a hybrid-type ZVsetup without changing any other equipment. A local control panel (114)is located in the field and connected to the ESD controller (110) inorder to control the solenoid valve (105) from the field to open andclose the ZV (106). In addition, the local control panel (114) may beused to send a command to the smart valve positioner (108) to performpartial stroke via the ESD controller (110). The local control panel(114) may be also used to control the process control equipment (112A,112B).

Referring to FIG. 2 , the operation of an embodiment of a ZV system(200) in a hybrid-type ZV setup is shown. Initially, during normaloperations, the ZV system (200) is operated as a conventional-type ZVsetup, bypassing the smart valve positioner (208). However, wheneverpartial stroke testing is required, the ZV system (200) is changed intoa smart-type ZV setup using the switchover kit (202). The switchingtakes place while the system is online without impacting safety orcausing process interruption. This helps overcome the issue ofunintended closure of the ZV due to smart valve positioner failure,while maintaining the main safety function of the ZV. Once the partialstroke testing is complete, the switchover kit (202) returns to aconventional-type ZV setup bypassing the smart valve positioner (208).

In the embodiment shown, the ZV system (200) includes an air supply(204), solenoid valve (205), ZV (206), an ESD controller (210), processcontrol equipment (212A, 212B), and local control panel (214) similar tothe elements shown in the block diagram of FIG. 1 . Accordingly, thecoupling and operation of the similar elements is not repeated. As canbe seen, in one or more embodiments, the switchover kit (202) mayinclude a plurality of valves (valve 1, valve 2, valve 3) forselectively bypassing the smart valve positioner (208) depending onwhether partial stroke testing is being performed or normal operationsare proceeding.

Referring to FIG. 3 , in accordance with one or more embodiments, a ZVswitchover kit (300) includes a manifold (302) having a plurality ofvalves (Valve 1, Valve 2, Valve 3) coupling an air supply (not shown), asolenoid valve (not shown), and a smart valve positioner (not shown).The several valves (Valve 1, Valve 2, Valve 3) as well as an air supplyport (304), a smart valve positioner air supply port (306), a smartvalve positioner output port (308), and a solenoid valve air supply port(310) may be configured to create, based on a first setting of theplurality of valves, a first air flow path through the manifold connectsthe air supply directly to the solenoid valve and, based on a secondsetting of the plurality of valves, a second air flow path through themanifold connects the air supply to the solenoid valve through the smartvalve positioner.

As can be seen, in the embodiment shown, the valves (Valve 1, Valve 2,Valve 3) are manual valves, however, as previously stated, in one ormore embodiments, automated valves may be employed that may becontrolled by a single ESD controller for the entire ZV system orseparate controllers respectively configured to specifically controleither the solenoid valve or the switchover kit. Those skilled in theart will appreciate other types of valves may be employed withoutdeparting from the spirit of the disclosed embodiments of the invention.

Referring to FIG. 4 , a method (400) of operating a ZV system in ahybrid-type setup as shown in FIGS. 2-3 may involve the followingprocess steps.

In a first step (402), before switching from conventional-typeoperations to smart-type operations, it should be confirmed that thesmart valve positioner is working by checking the smart valve positionerparameters utilizing the communicator. If the smart valve positioner isnot operating properly for any reason, then maintenance should beperformed on the smart valve smart valve positioner or the smart valvepositioner should be replaced (404). Once it is confirmed that the smartvalve positioner is functioning properly (402), the process cancontinue.

The steps to convert from conventional-type ZV to smart-type ZV forperforming the partial stroke testing during PM include:

In step (406), Valve 3 is opened, which allows the flow of air from theinstrumental air supply (IAS) port to flow to the smart valvepositioner.

In step (408), check whether the smart valve positioner gauge reads thepressure in order to determine that the airflow is being properlyreceived at the smart valve positioner. If the smart valve positioner isnot receiving the airflow properly for any reason, then maintenanceshould be performed on the smart valve positioner or the smart valvepositioner should be replaced (404). If the smart valve positioner isproperly reading the pressure of the airflow, then the process cancontinue.

In step (410), Valve 2 is opened, which allows the smart valvepositioner to supply air to the solenoid valve air supply port.

In step (412), Valve 1 is closed, which disconnects the directconnection between the IAS port and the solenoid air supply port,thereby only allowing air supply through the smart valve positioner.

The switchover kit remains in the smart-type ZV setup during partialstroke testing (414). Once the partial stroke testing has completed(414), the steps to return from the smart-type ZV to conventional-typeZV to continue normal operation include:

In step (416), Valve 1 is opened to re-connect the direct airflow pathbetween the IAS port and the solenoid air supply port.

In step (418), Valve 2 is closed, which disconnects the smart valvepositioner air supply port from the solenoid valve air supply port.

In step (420), Valve 3 is closed to disconnect the smart valvepositioner entirely from the system. By doing so, maintenance orreplacement of the smart valve positioner may occur while the system isstill online and operating.

As those skilled in the art will appreciate, during normal operations,the valves of the switchover kit are configured so that the ZV systemhas a conventional-type ZV setup. However, by switching the valves ofthe switchover kit into a smart-type ZV setup, partial stroke testing ofthe ZV can occur. Thereafter, once the partial stroke testing hasconcluded, the system can be returned to a conventional-type ZV setup.Thus, the switchover kit allows, based on a first setting of theplurality of valves, a first air flow path that connects air from theair supply directly to the solenoid valve controlling the ZV and, basedon a second setting of the plurality of valves, a second air flow pathconnects air from the air supply to the solenoid valve controlling theZV through the smart valve positioner. As described above, in one ormore embodiments, the switchover kit can be designed to work completelyindependently of the existing an ESD controller such that the switchoverkit can be retrofit onto existing ZV systems without changing thefunction of any other equipment.

Embodiments of the present disclosure may provide at least one of thefollowing advantages. One or more embodiments are low cost, easy andfast to build, and save production time by eliminating unwanted suddenclosures. Further, one or more embodiments provide a transfer mechanismfor switching between conventional-type operations and smart-typeoperations while the system is online. Also, one or more embodimentsallow the performance of maintenance on or replacement of positioners orthe internal parts of a positioner to occur while the system is online.Finally, one or more embodiments help prevent ZVs sudden closure due tofailure of a positioner.

Although only a few example embodiments have been described in detailabove, those skilled in the art will readily appreciate that manymodifications are possible in the example embodiments without materiallydeparting from this invention. Accordingly, all such modifications areintended to be included within the scope of this disclosure as definedin the following claims. In the claims, means-plus-function clauses areintended to cover the structures described herein as performing therecited function and not only structural equivalents, but alsoequivalent structures. Thus, although a nail and a screw may not bestructural equivalents in that a nail employs a cylindrical surface tosecure wooden parts together, whereas a screw employs a helical surface,in the environment of fastening wooden parts, a nail and a screw may beequivalent structures. It is the express intention of the applicant notto invoke 35 U.S.C. § 112(f) for any limitations of any of the claimsherein, except for those in which the claim expressly uses the words‘means for’ together with an associated function.

What is claimed is:
 1. An emergency shutdown (ESD) system for a processcontrol system comprising: an air supply coupled to a solenoid valveused to control a pneumatically-operated emergency isolation valve (ZV)via a switchover kit, a smart valve positioner coupled to the solenoidvalve via the switchover kit, an ESD controller configured to: controlthe supply of air from the air supply by the solenoid valve to open andclose the ZV, and control the smart valve positioner so as to perform apartial stroke test on the ZV; wherein the switchover kit comprises: amanifold having a plurality of valves coupling the air supply, thesolenoid valve, and the smart valve positioner such that: based on afirst setting of the plurality of valves, a first air flow path throughthe manifold connects the air supply directly to the solenoid valve, andbased on a second setting of the plurality of valves, a second air flowpath through the manifold connects the air supply to the solenoid valvethrough the smart valve positioner.
 2. The emergency shutdown system fora process control system according to claim 1, wherein the plurality ofvalves of the manifold of the switchover kit comprises: a first valvefor connecting/disconnecting airflow from the air supply to the solenoidvalve; a second valve for connecting/disconnecting airflow from the airsupply to the smart valve positioner; and a third valve forconnecting/disconnecting airflow from the smart valve positioner to thesolenoid valve.
 3. The emergency shutdown system for a process controlsystem according to claim 1, wherein the plurality of valves of themanifold of the switchover kit are manual valves.
 4. The emergencyshutdown system for a process control system according to claim 1,wherein the plurality of valves of the manifold of the switchover kitare automated valves controlled by a switchover kit controller, whereinthe switchover kit controller is separate from the ESD controller. 5.The emergency shutdown system for a process control system according toclaim 1, wherein the plurality of valves of the manifold of theswitchover kit are automated valves controlled by the ESD controller. 6.A method for operating and testing an emergency shutdown (ESD) systemfor a process control system comprising: an air supply coupled to asolenoid valve used to control a pneumatically-operated emergencyisolation valve (ZV) via a switchover kit, a smart valve positionercoupled to the solenoid valve via the switchover kit, an ESD controllerconfigured to: control the supply of air from the air supply by thesolenoid valve to open and close the ZV, and control the smart valvepositioner so as to perform a partial stroke test on the ZV; wherein theswitchover kit comprises: a manifold having a plurality of valvescoupling the air supply, the solenoid valve, and the smart valvepositioner, the method comprising: setting the plurality of valves in afirst setting such that a first air flow path through the manifoldconnects the air supply directly to the solenoid valve, setting of theplurality of valves in a second setting such that a second air flow paththrough the manifold connects the air supply to the solenoid valvethrough the smart valve positioner, performing partial stroke tests onthe ZV using the smart valve positioner only when the valves of themanifold are set in the second setting, and operating the emergencyshutdown system with the valves of the manifold set in the first settingat times when partial stroke tests are not being performed.
 7. Themethod according to claim 6, wherein the plurality of valves of themanifold of the switchover kit comprises: a first valve forconnecting/disconnecting airflow from the air supply to the solenoidvalve; a second valve for connecting/disconnecting airflow from the airsupply to the smart valve positioner; and a third valve forconnecting/disconnecting airflow from the smart valve positioner to thesolenoid valve.
 8. The method according to claim 6, wherein theplurality of valves of the manifold of the switchover kit are manualvalves.
 9. The method according to claim 6, wherein the plurality ofvalves of the manifold of the switchover kit are automated valvescontrolled by a switchover kit controller, wherein the switchover kitcontroller is separate from the ESD controller.
 10. The method accordingto claim 6, wherein the plurality of valves of the manifold of theswitchover kit are automated valves controlled by the ESD controller.